As for lifestyle changes, I'm not an expert in sleep science, but I've tried to read some of the literature to understand what works, since I struggle with sleep quality. As far as I can tell, a lot of the specific suggestions that often get thrown around (even by otherwise reputable sources, sadly) are somewhere between speculative and pseudoscience. There is some evidence that "sleep hygiene" interventions as a whole might have some kind of effect, but the individual components aren't typically tested, the studies usually aren't adequately controlled, and the effect is often exaggerated (e.g. by highlighting questionable measures like "sleep efficiency").
CBT-I has better evidence, although it's also not entirely clear which components are really worth the trouble (the evidence for sleep restriction seems pretty strong; the "CBT" elements less so, but it may be that they help different subpopulations), and clinicians who actually have experience delivering CBT-I are not readily available in many places.
It has helped me tremendously (together with other tooling like sport and meditation).